- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
What are 3 types of evidence provides support for the theory of seafloor spreading?
What three types of evidence provide support for the theory of sea-floor spreading?
Evidence from molten material, magnetic strips and drilling samples
support the theory of sea-floor spreading. What are deep ocean trenches?
What is the first step of sea floor spreading?
Plates that are not subducting are driven by gravity sliding off the elevated mid-ocean ridges a process called
ridge push
. At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers.
What are the main features of seafloor spreading?
Seafloor spreading produces major characteristics of the seafloor – 1) the age of the seafloor is progressively older away from midocean ridges, 2) the elevation of the seafloor is progressively lower away from midocean ridges, 3) the magnetic history of the seafloor bears the striped-pattern of the Earth’s magnetic …
What is the steps of seafloor spreading?
Seafloor spreading occurs at
divergent plate boundaries
. As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks.
What are 2 pieces of evidence supporting seafloor spreading?
Harry Hess’s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory. This evidence was from the investigations of
the molten material, seafloor drilling, radiometric age dating and fossil ages, and the magnetic stripes
.
Where is active seafloor spreading occurring today?
Where is active sea floor spreading occurring today? Seafloor spreading is the movement of old rock that is being pushed by the new young oceanic crust. This would be a divergent since the plates are separating from each other. Active seafloor spreading is occurring at
mid-ocean ridges
.
What evidence is used to support seafloor spreading?
The study of the repeated reversal of the Earth’s magnetic poles over time
has provided convincing evidence of seafloor spreading. Objective: To explore how magnetic studies and age information provide evidence for seafloor spreading that explains why oceanic crust is younger than continental crust.
What are the five steps of seafloor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
What causes the plates to move?
The heat from radioactive processes within the planet’s interior
causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
Do spreading centers move?
Spreading centers occur
where two plates are moving away from each other
, and deep cracks are opened through the crust. … Subduction zones are associated with regions where two plates are moving towards each other, and the crust of the earth is shortened.
Where are seamounts located?
Seamounts are commonly found
near the boundaries of Earth’s tectonic plates and mid-plate near hotspots
. At mid-ocean ridges, plates are spreading apart and magma rises to fill the gaps.
What happens when the seafloor spreads?
Sea-floor spreading is what happens at the mid-oceanic ridge where
a divergent boundary is causing two plates to move away from one another resulting in spreading of the sea floor
. As the plates move apart, new material wells up and cools onto the edge of the plates.
What are the features of seafloor?
Features of the ocean include
the continental shelf, slope, and rise
. The ocean floor is called the abyssal plain. Below the ocean floor, there are a few small deeper areas called ocean trenches. Features rising up from the ocean floor include seamounts, volcanic islands and the mid-oceanic ridges and rises.
Why is Earth not growing in spite of seafloor spreading?
New crust is continually being pushed away from divergent boundaries (where sea-floor spreading occurs), increasing Earth’s surface. But the
Earth isn’t getting any bigger
. … Deep below the Earth’s surface, subduction causes partial melting of both the ocean crust and mantle as they slide past one another.
Why is magma an indicator in seafloor spreading?
The Seafloor Spreading Hypothesis
The hot magma at the ridge erupts as lava that forms new seafloor
. When the lava cools, the magnetite crystals take on the current magnetic polarity. As more lava erupts, it pushes the seafloor horizontally away from ridge axis.
